Analog demonstrator and process of demonstration



June 9, 1964 J. J. HEIGL ETAL 3,

ANALOG DEMONSTRATOR AND PROCESS OF DEMONSTRATION Original Filed Nov. 13,1956 5 Sheets-Sheet 1 John J. Heigl dflmes Inventors Donald S. McArfhurBywf iymorney June 9, 1964 ANALOG DEMONSTRATOR AND PROCESS OFDEMONSTRATION Original Filed Nov. 13, 1956 J. J. HEIGL ETAL 3,136,887

5 Sheets-Sheet 2 fi -j.

John J. Heigl James A.Wilson Donald 3 McAri-h Inventors ByW ZWAHOI'HGYJune: 9, 1964 J. J. HEIGL ETAL 3,

ANALOG DEMONSTRATOR AND PROCESS OF DEMONSTRATION Original Filed Nov.13', 1956 5 Sheets-Sheet 3 I I I I I I I I I 6 METER READINGMICROAMPERES 2 Fl G. 5

DIAL No.4

I I I l l o |'o 2'0 3'0 4'0 5'0 e o 70 so 90 I00 DIAL READING John J.Heigl James A.Wilson Donald S. McArthur Inventors June 9, 1964 J. J.HEIGL ETAL 3,136,887

ANALOG DEMONSTRATOR AND PROCESS OF DEMONSTRATION Original Filed Nov. 131956 5 Sheets-Sheet 4 METER DEFLECTlON-MICROAMPERES ERROR OF FUNCTIONMAXIMUM 0 0 IO 20 3O 4O 5O 6O 7O 8O 90 I00 3 DIAL SETTING FIG.- 6

Inventors June 9, 1964 J. J. HEIGL ETAL ANALOG DEMONSTRATOR AND PROCESSOF DEMONSTRATION Original Filed Nov. 15, 1956 TO METER M FIG-I 5Sheets-Sheet 5 2o PlOl FIG 8 u? *f" I l f i I a I :9? l J i I LL 123 IanInventors MAflorney United States Patent 9 This application is adivision of an application Serial No. 621,763 filed in the United StatesPatent Ofiice on November 13, 1956, now Patent No. 3,027,083.

The present invention relates to an analog demonstrator and process ofdemonstration. It is applicable in general to the study of commercialoperations or processes involving variables known to be significantfactors bearing on the efficiency or economy of such operations orprocesses. It has particular application to such operations or processeswhere additional and unknown modifiers or variables need to be givenconsideration.

For example, in the study of a manufacturing process involvingconversion of raw materials into more valuable products, it may be knownthat processing time or reaction rate, temperature and pressure all havesignificant effects on the efficiency of conversion. If a study isundertaken to determine the optimum combination of these variables, arelatively large number of individual test runs may be required. In suchruns some of the variables may be held constant while one or two othersmay be varied. Even when the major variables are all known and are fewin number, ejg. three or four, the number of tests needed may be quiteexpensive. If, as is often the case, there are additional factors suchas variables which have not been isolated, but which introducesubstantial error into the results 'so that even a large number ofactual tests are inconclusive, the cost of study by experiment may wellbe- The problem is further complicated by come prohibitive.

factors which commonly the interdependence of certain occur.

As a more specified example, consider the case of a theoretical chemicalplant designed to make a synthetic product form certain specific rawmaterials. With a hypothetical optimum yield of a given percentage, theyield is assumed to be affected by five known factors, A, B, C, D and E.These might correspond respectively to temperature, pressure, feed rate,catalyst efiiciency and type of diluent, for example. It is suspectedthat other factors such as turbulence of mixing, high purity of feedstream, etc., may have an effect since practical experience has shownthat under apparently identical conditions A, B, C, D and E, the yieldwill vary by as much as, say, By taking into consideration thisadditional factor of error, which may be called F, and introducing it atvarious values under 5% picked from a normally distributed population(with average Zero), in effect the unpredictable error may besuperimposed upon the system. The present invention thus makes itpossible to complete a reasonably sound economic study of the plant,even when the factor F, or means for controlling it, are completelyunknown. Further specific examples are given below.

Hence it is an object of the present invention to simulate and todemonstrate by sensory indications, such as numerical readings, theeffect of both known and unknown operating variables in an art, processor industry, etc.

A further object is to make realistic demonstrations of the variableeffects of multiple factors of which some at least are interdependent.

A still further object is to design apparatus of relatively simple andinexpensive type for effective demonstration of dependent as well asindependent variables.

3,136,887 Patented June 9, 1964 ICC A more detailed object is toconstruct analog or demonstration equipment with provision for takinginto consideration at least one unknown or error factor along with thosevariables which are known or presumed to be significant. The inventioninvolves as another object the separation of major from minor variablesin the simulated study of operations, arts or processes. Such study canbe carried out with substantial reduction in costs as compared withconventional test and research methods.

Thus the invention involves the provision of a simple system, involvingapparatus capable of simulating commercial or industrial operations andpredicting with a reasonably good degree of accuracy the effect of oneor more unknown or unpredictable factors on a system of known variables.The known variables may be dependent or independent. Commonly some ofboth types are involved.

The invention will be more fully understood by reference to the attacheddrawings wherein:

FIG. 1 is a diagrammatic illustration of an electrical analog uni-tincluding electrical circuits embodying the invention;

FIG. 2 is a diagrammatic view of a circuit showing two variables only;

FIG. 3 shows several circuits for representing various types offunctions;

FIG. 4 shows the ganging of circuits to introduce interaction betweenseparate variables; 7

FIG. 5 shows relationship between dial reading and meter reading forindependent and interacting-variables;

FIG. 6 shows representation of an error function by a dial reading;

FIG. 7 shows a single unit component of an automatic error selector, andp FIG. 8 shows an automatic random error selector made up of a pluralityof the units of FIG. 7.

Referring now to the drawings, FIG. 1 shows a preferred arrangement oftwo interconnected units or boxes 11, 13, containing respectivelymechanism for simulating a plurality of known variables and means forreading in a random error value. Unit 11 comprises a group of circuitsdesigned to represent variable values. Each of these operates accordingto Kirchoffs laws to produce a certain definite electrical currentcontrolled by a dial setting. Beginning at the left, the first circuit Ccomprises a battery B .a fixed resistance R 8. lead line L from thenegative pole of the battery, a resistance R in parallel with this line,and an adjustable contact or potentiometer P adapted to adjust outputvoltage from circuit C toterminals T and 11.

Referring to FIG. 3, there are shown a group of circuits of which thesecond from the left, designated CA corresponds generally to circuit Cof FIG. 1. This is designed to represent a function which varies fromzero value through a maximum and back to zero as the potentiometer P isadjusted between its extremes. This unit C is thus suitable forrepresenting a variable that has zero effect at its extremes and maximumeifect at an intermediate level. The exact shape of the curve X FIG. 3,will depend on the nature of the winding R whether it is uiform orvariable, and on its relative magnitude compared with R The secondcircuit C of FIG. 1 is designed to simulate a function that increasesnon-linearly from zero value to its maximum, with a convex bend upwardlyas in curve X FIG. 3. Circuit C of this figure thus corresponds to CFIG. 1. Suitable values are given resistances R R R FIG. 3.

For a variable that increases slowly at first and then more rapidly, thenon-uniform resistance R R may be provided. It does not have acounterpart in FIG. 1. Linear variables X, are represented simply by alinear amass? potentiometer involving the simple single resistance RObviously, more complex functions require special types and combinationsof resistances but these generally can be contrived readily by thoseskilled in the art. Sources of potential indicated as batteries B B B EFIG. 3, obviously can be replaced with other conventional sources.

Before proceeding further with a description of FIG. 1, reference willnext be made to FIG. 2. Here are shown two interconnected circuits K andK whose combined output current is measured through a meter M In circuitK a potential source B tends to cause current to flow through resistanceR and set up a potential betweenterminals T and t The magnitude of thispotential, and possibly its direction, will vary with the setting ofpotentiometer P V At the same time circuit K with battery B supplyingpotential across resistances R and V tends to cause current to flow andsets up a potential between T and r If the two potentials are exactlyequal and opposed, meter M reads zero. Otherwise a voltage reading isobtained whose value and direction depends on the combined potentials ofthe two circuits.

Referring back now to FIG. 1, circuits C C and C may all be adjusted torepresent variable factors or func-.

tions whose individual characteristics are known. Assuming for themoment that all of the variables to be represented are independent,dials (not shown) may be setto desired readings in adjusting each of thevariable potentiometers P P P P and P When all are set,

the total potential T t will be transmitted through leads L L to themeter box. If these leads were connected to a meter M in unit 13, itwould read the cumulative effect of circuits C to C directly. Such areading would have some definite value. By adjusting the five dials thatcontrol potentiometers P to P maximum (or minimum) readings could beobtained by trial and error. If the five circuits represent all thefactors that affect an operation, for example a chemical process, thisrelatively simple series or adjustments would eliminate numerous andtedious computations hitherto needed for establishing, say, theconditions needed for maximum yields. The various resistances incircuits C to C need not be described in detail.

In many cases, however, there are other and unknown variables that alsoaffect the end result, e.g. the yield in the case of a chemical process.In tests with a pilot plant, for example, it is often found that witheven the most careful attempts to duplicate earlier runs, results arenot identical. Frequently they differ rather widely. The differences aredue, of course, to unknown factors or variables, i.e. errors.

To allow for unknown variables or errors, the readout unit has inaddition to its meter a circuit C Preferably t his unit 13 issufficiently remote from unit 11 and the connections sufficientlyflexible so that it can be operated and read by a separate operator.Errors or arbitrary settings for circuit C can be introduced by thisindependent operator at random. In this way, direct control of theerrors is taken away from the primary operator in his efforts toestablish optimum conditions of the known variables.- Where the errorsare not too large, a working optimum may readily be obtained. If theerrors are so large that the known variables are incapable of adjustmentto an optimum, further research to break down the errors into knownvariables becomes mandatory.

As shown, circuit C comprises batteries or equivalent sources ofpotential B and B A double pole double throw switch S is provided forselectively completing circuits which include or exclude the batteries.With the batteries in circuit, a positive or a negative potential may beapplied to a resistance R of variable potentiometer P depending on itssetting. By reversing, the positive potential of incoming line L isapplied to resistance R and R THence, potential across terminals T and Tmay be either positive or negative and of any magnitude suitable forrepresenting errors to be read into the system. The absolute magnitudeof such errors, of course, is determined experimentally by notinguncontrollable variations in data when pairs or other combinations ofthe known variables C to C are kept constant. p

The potentiometer P like P to P is provided with a dial (not shown) sothat absolute values of the error, positive or negative, may be read atrandom and arbitrarily introduced into the system. The overall readingresulting from adjustment of all the known variables plus thesuperimposed random error, which may have any value from zero tomaximum, positive or negative, is then read out on meter M. It isusually preferable to have meter M read by the error operator so that itcannot be adjusted by the primary operator who is striving to establishoptimum values for all the known variables the error thus being out ofhis control.

In FIG. 4 means are shown for operatingtwo of the known variablecircuits together. This is obviously needed when the two are known to beinterdependent. Circuit 0,; has a battery or other source of potential Bfrom which current flows through resistances R R and through variablepotentiometer P resistances R and R By adjustment of potentiometer P adesired value may be set up acrossv terminals T and i In circuit C abattery or source of potential supplies current to resistances R and Rand potentiometer P is variable to set up a desired value acrossterminals T and The otentiometers, P and P1 are connected together,either for similar movement if the relation between the variables theyrepresent is linear, or for movement according to some otherrelationship as may be required when the relation is non-linear.

Obviously 3, 4 or more variables may be linked together for simultaneousadjustment when their interdependence and their relation to each otheris fully known. This type of linking obviously greatly simplifies thestudy and should be used wherever possible.

FIG. 5 shows graphically different functions that might be traced ondial Nos. 1, 3 and 4, corresponding to circuits such as C C and C Theabscissa represents the dial reading in units of 1 to and the ordinatethe meter reading, M, in microamperes.

FIG. 6 shows graphically the error function that might be read into thesystem by arbitrarily setting the dial which controls circuit C Themeter deflections M are shown at the left and the percentage value ofthe error, as compared with the maximum value to be obtained on thestudy is shown at the right. The dial setting is indicated at thebottom.

Instead of having the normal distribution curve error set into thesystem by an independent human operator, this can be done by automaticmeans. An electronic device, a normal distribution curve generator, isshown in FIG. 8 for this purpose. The device is made up of a pluralityof components of the type shown in FIG. 7.

Referring to FIG. 7, there are shown two gas discharge tubes, such asneon bulbs 101 and 103. A voltage is impressed across leads 105 and 107.The respective neon tubes are connected to lead 105 and are alsoconnected together by a resistance 109 which makes contact with amovable contact element 111 attached to the line 107. By this means thevoltage impressed on the respective gas discharge tubes 101 and 103 maybe varied. A condenser 113 is connected in parallel with resistance 109and this may be shorted out by another parallel cir cuit 115 having aswitch 117.

When the switch 117 is open the impressed voltage causes a charge tobuild up on condenser 113. Ultimately one of the gas discharge tubes 101or 103 flashes and discharges the condenser on its side. The charge thenbuilds up on the opposite side until the other gas discharge tubedischarges, and thus an oscillating circuit is established with the gasdischarge tubes flashing alternately at a frequency that may be variedfrom a few Q to many hundred cycles per second. The oscillation is ofsufiiciently high frequency that when the switch 117 is closed to keepone of the gas discharge tubes on, and

. the other shut off, it is not possible for the operator of the switchto exercise control over which gas discharge tube will be kept glowing.

Referring now to FIG. 8, there are shown three units like FIG. 7connected in parallel. Appropriate voltage is impressed on all threecircuits by a battery 121 through leads 123 and 125. The units U401,U403 and U-105 operate exactly like the single unit in FIG. 7. Each ofthem has a switch 117, the switches all being ganged together at 118.When the switches are closed the operator has no way of deciding whichtubes will be kept glowing because the frequency of oscillation in eachof the units is too rapid for him to make any selection by choice. Hemay be chance close the circuits at a time when-all three of the tubeson the right are glowing or he may catch all three units on the leftglowing. On the other hand, he may catch one or two on one side and twoor one on the other. Obviously, for greater selectivity and morecomplete random distribution, the number of units should be greater thanthree and normally will be several times that number. For simplicity ofexplanation, however, only three are shown.

It will be understod, then, that when the operator closes the gangswitches 117, 118, certain tubes will be lighted, the distribution beingaccording to the probability curve. By measuring the current passingthrough the discharge tubes or the amount of light generated on eachside of the apparatus, the random error introduced into meter M, FIG. 1,may be thrown into the circuit without any premeditated control as toits magnitude or polarity.

In FIG. 8 a simple means for measuring the magnitude of-the error isprovided. The amount of light on each side of the unit is measured by aphotocell 1 -101 or P- 103. It will be understood that the gas dischargetubes '-will be arranged sufficiently close to the photocell and thelight therefrom directed towards it so that each photo- -cell willmeasure only the light from the tubes on its side of the device. If onlythe discharge tubes on the right are glowing, the tube P-101 willregister maximum current and introduce the maximum error of one predetermined polarity. Similarly, the maximum error of opposite polaritywill be introduced when the photocell P-103 shows all of the tubes onits side to be lighted. Errors of lesser absolute values will beintroduced when some of the tubes on both sides are lighted.

Alternatively, the current may be measured in each bankof gas dischargetubes after switch 117 is closed. The relative amount of current flowingis a measure'of the number of gas discharge tubes remaining lighted ineach bank and can be used as a measure of the part of the normaldistribution curve selected. This is transmitted to meter M, FIG. 1,through a control device D and superimposed on the current from theunits under direct operator control.

By the means just described, an error within the desired limits ofmagnitude may be introduced into the system. Since the magnitude willvary for different problems, the current from the photocell to the meterM may be amplified to varying degrees for each problem. Means for suchamplification are obvious to those skilled in the art and arenot shownon the drawings. It will be notedthat the output of the device of FIG. 8can be connected to the meter M of FIG. 1.

The manner in which the normal distribution curve error is introducedwill vary, depending upon the particular application of the analogdemonstrator. In some cases, the output from the normal distributioncurve generator is connected directly to the output circuit of theanalog demonstrator through a control device D so that each analogdemonstrator output reading contains an error factor. In other cases,the output from the normal distribution curve generator is noted by anoperator, be-

fore the error factor is introduced into the system. By methods obviousto those skilled in the art, the output from the normal distributioncurve generator as well as the output from the analog demonstrator canbe automatically recorded, along with the corresponding dial settings.

In applying the system to study of a concrete problem, various operatorsand teams of operators are found to vary in their skills. In a simulatedprocess for producing a synthetic alcohol from raw materials, forexample, it was postulated that an expected yield of 24% was beingobtained with a. standard group of settings, but that a higher yield,something less than 50%, was theoretically possible. It was determinedthat there were five known variables, X being important with a maximumat about 18, X, with a maximum around '67, X less important, essentiallylinear, with a maximum at about 94, X; of no effect in the presentexample, and X almost linear, maximum at about 95. A standard deviationof 4% constant throughout the yield range was postulated. It was desiredto increase the yield by doing empirical research work. Assuming thateach plant test costs $20,000 and that a 1% improvement in yield isworth $50,000 per year, or $500,000 over a predicted ten-year life ofthe plant, the problem was presented to the research teams to improvethe plant yield, i.e. to determine What research could be done and howlong it should be continued.

Obviously, if the researcher could get a yield improvement of 10% after50 tests, he would have earned 4 million dollars net, or $5.00 for eachresearch dollar spent. Another, after only 4 tests costing 80 thousanddollars might get a 2% improvement with 1 million dollars or $12.50 foreach research dollar, but far below the potential. This shows thatreturns per dollar spent are not necessarily the best criterion forjudging the efficiency of research. 7

Strategy in research work can be studied by this method, e.g. whetherthe one-variable at a time technique or a bolder strategy ofpredetermining several values 'at once is the most profitable. Thesuperimposition of the random error is realistically frustrating to theresearch team but it is deemed essential. The random error is eithercase is selected according to the law of probability, with appropriatelimits, and is not under control of the operator, or at least not undercontrol of the primary operator.

The apparatus and the method of using it obviously are adaptable tovarious problems, such as plant operations, underground flow of oildeposits, economic operations of various types, etc. Many variations indetails of equipment and in method of their use will appear obvious tothose skilled in the art. It is intended to cover such herein so far asthe prior art permits. I What is claimed is:

Means for impressing a superimposed random electric current of randomvalue within known limits according to the law of probability,comprising a source of electric current, two opposed series of gasdischarge tubes, one tube of each series being paired with a tube of theother series in order to pass electric current from said source in rapidalternation at a frequency too high for'human control, a gang ofswitches, said switches being closed simultaneously across all the tubesso as to maintain the instantaneous flow of current through the tubesthat are flowing for a measurable period of time, whereby the closing ofthe switches arbitrarily selects a total current value in one series orthe other that is within predetermined limits but selected according tothe law ofprobability within those limits and not quantitatively undercontrol of the operator.

References Cited in the file of this patent I I UNITED STATES PATENTS2,359,747 Carleton Oct. 10, 1944 UNITED STATES PATENT OFFICE CERTIFICATEOF CORRECTION Patent No, 3, 136,887 June 9 1964 John J, Heigl et alo Itis hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 5 line 17, for "be" read by column 6 line 65 for "'flowing readglowing Signed and sealed this 13th day of April 1965 (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

